1. Field of the Invention
The present invention is generally related to an apparatus and a method for suctioning a predetermined volume of liquid and discharging the suctioned liquid to a location to be dispensed.
2. Description of the Related Art
Currently, a high-throughput screening of biological samples and drug discovery samples, such as nucleic acids, proteins and peptides, and a comprehensive analysis of organisms are strongly needed. In addition, targets having unstable natures such as biologically relevant materials are often used as samples handled in those fields. In those fields, automatically dispensing apparatuses capable of dispensing multiple types of sample solutions in a narrow area such as several centimeters squares, on a substrate, such as a glass slide at a high density with a short cycle time are needed.
The automatically dispensing apparatus is typically provided with a dispensing head having a plurality of nozzles such as pipette chips, and automatically conduct a process of taking desirable volumes of sample solutions from a sample solution reservoir with the nozzles of the dispensing head, a process of dispensing the taken sample solutions from the nozzles at predetermined positions on a substrate, and a process of cleaning the nozzles or exchanging the nozzles into unused new nozzles. Standard microtiter plates having 96, 384 or 1,536 wells are typically used as a sample solution reservoir for containing the sample solutions. The wells in the microtiter plates are arrayed at array pitches of 9 mm, 4.5 mm or 2.5 mm.
Dispensing pitches when dispensing a liquid on the substrate are often from several tens of micrometers to several hundreds of micrometers. Therefore, when dispensing sample solutions contained in the sample solution reservoirs including the microtiter plates on a substrate, it is necessary to change the array pitch of the nozzles of the nozzle head.
For example, Japanese Patent Laid-Open No. 2001-99847 and Japanese Patent Laid-Open No. 2001-211873 disclose variable pitch mechanisms capable of change an array pitch between arrayed nozzles of a dispensing head.
However, in the variable pitch mechanisms, there is a limit on narrowing the array pitch, because the variable pitch mechanisms change the array pitch by moving the entire nozzles. Accordingly, it is difficult to adapt the variable pitch mechanisms to dispensing intervals of from several tens of to several hundreds of micrometers.
Additionally, in the above technical fields, it is required to control small dispensing amounts of liquids having at least a volume of microliter order, and it is also required to control extremely small dispensing amounts of liquid having a volume of nanoliter order.
However, it is difficult for the conventional automatically dispensing apparatuses to control precise dispensing amounts of liquids having a volume of nanoliter order.